<scp>CEACAM5</scp> is an <scp>IL</scp>‐13‐regulated epithelial gene that mediates transcription in type‐2 (<scp>T2</scp>) high severe asthma
Authors: Sharon Mumby, Nazanin Zounemat Kermani, James P. Garnett, Stelios Pavlidis, Susan J. Wilson, Peter J. Howarth, Matthew J. Thomas, Ian M. Adcock, Carlos López‐García
Journal: Allergy (2022)

Severe asthma (SA) is a heterogeneous disease characterized by airflow restriction, frequent exacerbations and lack of effective treatments that improve quality of life and prevent exacerbations. The airway epithelium is remodelled in patients with SA and plays a pivotal role in orchestrating airway inflammation.1 However, airway epithelial cell-directed therapies have not been explored due to the lack of specific targets. We interrogated the data from the U-BIOPRED consortium2 to identify cell surface proteins as potential targets to treat SA. CEACAM5, an adhesion protein, was the most highly upregulated gene in bronchial brushings (containing all epithelial lineages) obtained from patients with SA, but not significantly upregulated in mild–moderate asthmatics (Figure 1A, Table S1). CEACAM5 upregulation was greatest in patients with T2-SA (Figure 1B), which suggested a role for T2 inflammation in CEACAM5 upregulation. Our analysis also showed an increase in CEACAM5 expression in patients with frequent exacerbations and in patients with persistent airflow limitation (Figure S1A, B, respectively). Immunohistochemical analysis of bronchial biopsies confirmed CEACAM5 upregulation in the bronchial epithelium of SA patients (Figure 1C, D and Figure S1C) and subcellular localization in intraepithelial cell junctions, the apical end of epithelial cells and perinuclear cytoplasmic regions (Figure 1E). Interrogation of the Lung Cell Atlas3 (https://asthma.cellgeni.sanger.ac.uk/) showed that CEACAM5 is expressed more prominently in differentiated cells than in basal cells. (Figure 1F, G). The treatment of organotypic air–liquid interface (ALI) cultures generated from human bronchial epithelial cells (HBECs) (Figure 2A) with representative factors implicated in the pathogenesis of asthma showed that the T2 cytokine IL-13 increased CEACAM5 expression (Figure 2B, Figure S1D–F) and the expected increase in MUC5AC (Figure S1G). CEACAM5 protein upregulation was confirmed by immunofluorescence (Figure 2C) and was detected in cell junctions (white arrows), apical (yellow arrows) and perinuclear cytoplasmic localizations (magenta arrows) (Figure 2D) of ALI cultures. These results confirmed that CEACAM5 epithelial expression is regulated by IL-13 and that its localization is consistent with our observations in patients. Next, we hypothesized that CEACAM5 overexpression mediates some of the epithelial cellular and molecular changes driven by IL-13 in T2 severe asthmatics. To address this, we treated ALI cultures with IL-13 in the presence or absence of labetuzumab (Figure S2A), a therapeutic CEACAM5 targeting antibody used in preclinical cancer studies.4 Labetuzumab did not prevent the changes in MUC5AC and FOXJ1 expression (goblet and ciliated cell markers, respectively), or altered epithelial barrier function induced by IL-13 (Figure S2B–D). However, RNAseq analysis showed that labetuzumab dysregulated 80 genes in IL-13-treated ALIs (simultaneous IL-13 and labetuzumab treatment compared with IL-13 only) (Figure 2E–F and Table S2) with an enrichment in interferon-regulated genes (Table S3). Forty-two of these genes were also IL-13-regulated genes (IL-13-treated ALIs compared with untreated controls) (Figure 2G), 30 of which were regulated in a reciprocal manner (Table S4). The effect of CEACAM5 targeting on partially preventing, or reversing, IL-13 transcriptional activity was more marked for IL-13-downregulated genes (Figure 2H and Table S4), together with an enrichment in interferon-inducible genes (Table S5). These results confirm that a subset of the IL-13 transcriptional epithelial signature is mediated by CEACAM5. CEACAM5 targeting with labetuzumab does not impair the IL-13-driven epithelial remodelling but affects IL-13-dependent and IL-13-independent gene expression. Although anticipating the potential therapeutic benefit of labetuzumab in severe asthmatics based on our data is premature, our results strongly support the use of CEACAM5 targeting agents in preclinical models to explore potential patient benefit. Importantly, restoring the epithelial interferon pathway as a means of treating asthma is supported by the literature.5 Additionally, CEACAM5 is known to bind respiratory pathogens involved in exacerbation6 and blocking this binding could prevent exacerbations. We thank the U-BIOPRED consortium for access to patient data and the Computational Biology Support at the Cancer Research UK Manchester Institute (University of Manchester) for their help with the RNA-seq analysis. We thank Tankut G. Guney, Professor Kian Fan Chung and Pankaj K. Bhavsar (Imperial College London) for technical support and insightful discussions. This project has been funded mainly by Boehringer Ingelheim Pharma GmbH with additional support provided by the CRUK Lung Cancer Centre of Excellence. MJT, PH and SP are employed by pharmaceutical companies. IMA has received grants from Boehringer-Ingelheim Pharma GmbH (lead applicant) and GSK (grant to institution), consulting fees from GSK, Sanofi, Chiesi and Kinaset, lecture fees from AstraZeneca, Sanofi, Eurodrug and Sunovion, support for expert testimony from Chiesi and support for meeting attendance from AstraZeneca. The other authors do not have any conflicts of interest to declare. Appendix S1 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.